Add voicemail tab if there are active providers.

Bug: 21328994
Change-Id: Id6cd45c5614fafcc6f01842a8ec1eaba45dc0928
diff --git a/res/values/strings.xml b/res/values/strings.xml
index e3b2682..21cd890 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -471,12 +471,19 @@
          [CHAR LIMIT=30] -->
     <string name="call_log_voicemail_title">Voicemail</string>
 
+    <!-- Accessibility text for the tab showing recent and favorite contacts who can be called.
+         [CHAR LIMIT=40] -->
     <string name="tab_speed_dial">Speed dial</string>
 
+    <!-- Accessibility text for the tab showing the call log of recent calls. [CHAR LIMIT=40] -->
     <string name="tab_recents">Recents</string>
 
+    <!-- Accessibility text for the tab showing the user's contacts. [CHAR LIMIT=40] -->
     <string name="tab_all_contacts">Contacts</string>
 
+    <!-- Accessibility text for the tab showing the user's voicemails. [CHAR LIMIT=40] -->
+    <string name="tab_voicemail">Voicemail</string>
+
     <!--  Text displayed when user swipes out a favorite contact -->
     <string name="favorite_hidden">Removed from favorites</string>
     <!--  Text displayed for the undo button to undo removing a favorite contact -->